In particular, they should not be needed in articles — with the following exceptions:

Template:' may be used as a replacement for <nowiki>'</nowiki> to "protect" an apostrophe character from being interpreted as part of the wikicode for italics (''), bold text ('''), or bold italics (''''') — something that should actually happen quite rarely in article text.

Template:! might (again, rarely) be useful in tables when you want to get a visible pipe character (|) but it's being mistakenly interpreted as an element of wiki table syntax (the usual symptom of this being that the text immediately before the pipe character is not showing up either).